This invention relates to a water-containing plastic composition. More particularly, this invention relates to a composition which comprises a water-containing gel as a dispersed phase obtained by subjecting a water-soluble polymer while it is in the form of an aqueous solution, to crosslinking reaction and a variety of plastics as a matrix (or continuous phase).
In recent years, plastics have made remarkable inroads into the field of construction materials and are continuously increasing this tendency. Plastics owe their usefulness in this new field to their excellent properties such as light weight, excellent workability, beautiful appearance and heat-insulating properties. On the other hand, the readily combustible nature of such plastics is a drawback to increasing the proportion of plastics used in construction materials. Thus, studies are now being made of ways to render plastics poorly combustible. One suggested treatment for rendering plastics poorly combustible involves the incorporation of a halogen-containing or phosphorus-containing combustion-inhibiting agent which, on combustion, emits a toxic or harmful gas or the use of a poorly combustible plastic resin such as polyvinyl chloride which certainly exhibits poor inflammability but emits a toxic gas on combustion. As these toxic and harmful gases are seriously dangerous to the health of humans and animals, the question of whether or not a toxic or harmful gas evolves at the time of combustion an additional consideration which must be taken into account. Accordingly, there is a great demand in the field of construction materials for the development of a new type of plastic material which exhibits good combustion-resisting properties without the evolution of either toxic gas or harmful gas upon heating.
On the other hand, it is known that water can be dispersed into plastics to impart combustion-resisting property to them. Heretofore reported in the art are, for example, a process for forming water-containing plastics which comprises preparing a water-in-oil emulsion containing a monomer and then polymerizing the monomer in such state (Japanese Pat. Publn. No. 31771/Showa 47), a process wherein a water-in-oil emulsion containing an unsaturated polyester is molded under curing conditions in the presence of a catalyst (Japanese Pat. Publn. No. 12437/Showa 48), and a process wherein water-containing microcapsules are mixed with a thermocurable plastic substance and the mixture is molded under curing conditions (Japanese Patent Publn. No. 35694/Showa 48). However, these processes have not yet been perfected for practical use because of the complicated operations and special apparatus necessary to carry them out and the difficulty in homogeneously dispersing large amounts of water into plastics and still obtaining products with satisfactory strength.